Atlantoaxial Rotatory Fixation

KEY FACTS

Imaging

• Abnormal rotatory motion of C1 with respect to C2 defined by 3-position CT scan

Top Differential Diagnoses

• Etiologies of atlantoaxial rotatory fixation (AARF)

  • Trauma

  • Nasopharyngeal infection (Grisel syndrome)

  • Prior head and neck surgery

Pathology

• Pang type I AARF : Unaltered or locked C1-C2 coupled configuration regardless of corrective counter-rotation

• Pang type II AARF : Reduced C1-C2 separation angle with forced correction but C1 does not cross C2

• Pang type III AARF : Show C1-C2 crossover but only with head turned far to opposite side

Clinical Issues

• Persistently rotated head that is painful during attempts at correction (painful torticollis)

• Head typically laterally flexed on side opposite to pointing chin (cock-robin appearance)

• Treatment in acute phase gives best outcome (Pang type I-III)

Diagnostic Checklist

• Fielding-Hawkins type III, IV involve traumatic rupture of transverse atlantal and other stabilizing ligaments

  • Emergent and serious injuries require immediate surgical intervention to protect cord

  • These more serious injuries are separate from pure rotatory fixations, which are never acutely unstable (as in Pang type I-III AARF)

TERMINOLOGY